1. Field of Invention
The subject matter of the claimed invention is a ball and socket bearing including a metal ball and an outer race or socket formed thereover of filament-reinforced material having a low friction bearing surface in direct contact with the ball. The ball is of the type having a central bore therethrough and circular, flat end faces normal to the axis of the bore. The width of the ball refers to the distance between said ends.
The outer race or socket as formed on the ball has a spherical inner diameter corresponding to the outer diameter of the ball. The outer race or socket has parallel ends and the distance therebetween is considered the width of the socket. Normally the width of a socket is less than the width of the ball to allow their relative angular movement while the socket remains in full contact with the ball. That is, the ball normally has "projecting ends." For convenience also in describing the present invention, the area of athe ball between said ends will be referred to as the "socket area" of the ball.
In use, the socket of the bearing assembly is supported and secured withing a rigid housing. For that purpose, the socket is finished so that it has a cylindrical outer dimension to fit therein.
It is commercially important that the ball have a certain torque before and after the socket is secured in the supporting housing. This torque is the force in inch/pounds which is required to turn the ball in the socket and on the axis of its bore. Zero torque denotes a ball of maximum looseness.
The socket should therefore fit in the housing so that only axial securement is required and may be provided by bonding or with any suitable locking rings or swaged collars. This also means that the socket must be self-supporting axially and presents a particularly difficult strength requirement as will be described.
2. Description of the Prior Art.
In the manufacture of metal sleeve bearings, cutting a long tube to multiple lengths to comprise the sleeves is itself a common expedient. The internal bearing diameter of the individual sleeves can then be finished separately. Even after finishing, the diameter of the bearing may be made larger or smaller within limits, by well known means.
In the manufacture of metal ball and socket bearings, the sockets may be expanded after their completion to provide the desired fit. Typically, such assemblies when completed are tested for their torque and grouped accordingly. Those which are not too tight can be loosened by compressively stressing the outer portions of the metal forming the sockets.
This cut and try procedure for bearings with metal sockets cannot be used for bearings having outer sockets of other materials. Such sockets including those of the present invention must have the desired fit as and when completed.